FIG. 1 is a block diagram illustrating a conventional mobile communication terminal. As shown in FIG. 1, the conventional mobile communication terminal includes a transceiver 101 having a transmitter 111 and a receiver 113, a power amplifier 103, an isolator 105, a duplexer 107, and an antenna 109.
According to a signal transmitting process, the transceiver 101 transmits a signal through the transmitter 111, and the power amplifier 103 amplifies the transmitted signal. The isolator 105 prevents the system from being damaged by preventing the amplified signal from being reflected, and the duplexer 107 prevents a received signal from interfering a transmitting signal transmitted from the isolator 105. Then, the antenna 109 transmits a signal outputted from the duplexer 107.
According to a signal receiving process, the antenna 109 receives a signal, and the duplexer 107 prevents the transmitting signal from interfering the receiving signal. The receiver 113 receives a signal outputted from the duplexer 107.
FIG. 2 is a diagram illustrating a mobile communication transceiver shown in FIG. 1. As shown in FIG. 2, in the transmitter 111 of the mobile communication transceiver, a transmitting signal outputted from a base band system passes through an automatic gain control (AGC) and an intermediate frequency band pass filter (IF BPF), and a mixer modulates the passed signal using the signal of voltage controlled oscillator (VCO) as a reference. A drive amplifier (DA) amplifies the modulated signal, and the amplified signal is transmitted to a power amplifier (PA) through a radio frequency band pass filter (RF BPF).
In the receiver 113 of the mobile communication transceiver, a low noise amplifier (LNA) reduces noises of a receiving signal and amplifies only an original signal. A mixer demodulates the amplified signal after the amplified signal passes through the RF BPF, and the demodulated signal inputs into a base band system after passing through the AGC and the IF BPF.
FIG. 3 is a conventional mobile RFID reader. As shown in FIG. 3, the conventional mobile RFID reader includes a mobile RFID transceiver 301, a power amplifier 303, a circulator or a directional coupler 305, and an antenna 307.
According to a signal transmitting process, the mobile RFID transceiver 301 transmits a signal through the transmitter 309, and the power amplifier 303 amplifies the transmitted signal. The circulator or the directional coupler 305 separates the amplified signal from a receiving path, and the antenna 307 transmits the signal outputted from the circulator or the directional coupler 305.
According to a signal receiving process, the antenna 307 receives a signal, and the circulator or the directional coupler 305 separates the received signal from a transmitting path. The mobile RFID transceiver 301 receives the signal outputted from the circulator or the directional coupler 305 through the receiver 311.
Since the transmitting frequency and the receiving frequency are identical in the mobile RFID reader, the mobile RFID reader uses the circulator or the directional coupler for separating a transmitting signal path from a receiving signal path in order to reduce interference between the transmitting signal and the receiving signal.
FIG. 4 is a block diagram illustrating a mobile RFID transceiver of FIG. 3. As shown in FIG. 4, in a transmitter 309 of the mobile RFID transceiver, the transmitting signal passes an intermediate frequency band pass filter (IF BPF) and a modulator modulates the transmitting signal with a signal of a local oscillator LO as a reference. The modulated signal passes through a radio frequency band pass filter (RF BPF), and a drive amplifier (DA) amplifies the modulated signal and transmits the amplified signal to a power amplifier (PA).
In a receiver 311 of the mobile RFID transceiver, a receiving signal passes a radio frequency base band filter (RF BPF) and a demodulator demodulates the receiving signal using the signal of the LO as a reference. The demodulated signal passes through an intermediate frequency base band filter (IF BPF), and a gate amplifier (GA) amplifies the demodulated signal outputted from the IF BPF and transmits the amplified signal to a base band system.
As described above, the mobile communication terminal and the mobile RFID reader commonly include the power amplifier 103 or 303. Since a mobile communication terminal having a mobile RFID function is embodied by combining the mobile communication system and the mobile RFID reader, the mobile communication terminal having the mobile RFID function has two power amplifiers. One is for the mobile communication terminal and the other is for the mobile RFID reader. Therefore, the mobile communication terminal having the mobile RFID function has a problem of a complicated structure.
Since the power amplifier is large and consumes a great deal of power, the physical size of the terminal having two power amplifiers becomes larger and the power consumption thereof becomes increased.